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This invention relates to a tack-in apparatus adapted
to draw an end portion of weft yarn into a warp yarn opening
with an injection air current.
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There is a related art tack-in apparatus provided on both
sides of a woven fabric on a shuttleless loom, and adapted to
temporarily retain after weft insertion and beating are carried
out an end of weft yarn cut to a required weft insertion length
and thereafter tack this weft yarn end in a warp yarn opening
with an injection air current. In addition, in the tack-in
apparatus in the shuttleless loom disclosed, for example, in
Japanese Patent Laid-Open No. 49550/2001 of the applicant of
the present invention, a weft yarn end gripping unit for
temporarily retaining a weft yarn end, and tack-in nozzles for
blowing the weft yarn end to the side of a cloth fell with an
injection air current and thereby tack in the same are formed
in a single nozzle block.
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Injection ports of the tack-in nozzles are opened in the
side surface of the nozzle block which is opposed to a warp
yarn array, and two tack-in nozzles are provided on the discharge
side of the cloth fell and on both the upper and lower sides
of a position of the height of a warp line which constitutes
a weft yarn path when a beating operation is carried out. The
tack-in nozzles are communicated on the inner side of the nozzle
block with an air passage, which is joined to a regulator and
a pressure air source via change-over valves. The opening and
closing of each change-over valve is controlled automatically
by a control circuit.
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In the case of this related art apparatus, the warp yarn
in the vicinity of an end portion of the woven fabric is disordered
by the injection air diffused from the tack-in nozzles during
a tack-in operation, and a space formed between upper and lower
warp yarn when the warp yarn is opened varies. Consequently,
a weft inserting operation was carried out unstably. There
was the possibility that the injection air impinged forcibly
upon the warp yarn to cause the same to be broken, and that
an uneven woven fabric in which the condition of the portion
thereof which was in the vicinity of a selvage thereof and that
of a central portion thereof were different was formed.
Especially, in a pile fabric, which is greatly influenced by
an air injection current due to a low tensile force of pile
warp yarn, uneven formation of pile and breakage of pile warp
yarn occur. This caused the quality of the fabric to lower.
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In order to improve the convergence of the air injection
current, the inclining of both of the upper and lower tack-in
nozzles toward a warp line, and the crossing of the axes of
the tack-in nozzles each other were done. However, when the
tack-in nozzles are inclined greatly, a speed component toward
a warp yarn opening decreases to cause a weft yarn end transfer
force during a tack-in operation to lower and the injection
air currents to interfere with each other greatly. Consequently,
a turbulent flow occurred to cause the weft yarn transfer force
to further lower.
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The present invention has been made in view of the
above-mentioned circumstances, and provides a tack-in
apparatus capable of directing injection air currents toward
a central portion of a warp yarn opening at the time for carrying
out the tacking-in of a weft yarn end; transferring the weft
yarn end reliably and carrying out a tack-in operation; and
reducing the turbulence of the warp yarn.
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The present invention relates to a tack-in apparatus
provided with a cutter for cutting weft yarn after the weft
insertion is carried out, and tack-in nozzles for folding back
an end portion of the weft yarn cut with the cutter into a warp
yarn opening with injection air currents, injection ports of
the tack-in nozzles being opened in at least one of upper and
lower sides of a path which the weft yarn passes by a beating
operation, in which apparatus air guides projecting toward the
warp yarn opening are formed between the parts of the weft yarn
path which are in the vicinity of circumferential portions of
the injection ports and the same injection ports. The surfaces
of the air guides which are on the sides of the injection ports
may be inclined toward the weft yarn path as the surfaces extend
closer to front ends of the guides.
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The injection ports in one embodiment are formed
in a nozzle block provided adjacently to a warp yarn side portion
of the cutter. This nozzle block is provided with a slit which
is opened in three directions, i.e. , toward the warp yarn side,
discharge side and cutter side, and which extends along the
weft yarn path, and a weft yarn end releasing nozzle opened
at an injection port thereof into the slit and blowing the weft
yarn end in the slit toward the discharge side of the slit via
injection air. Not less than one injection port of the tack-in
nozzles is opened in the portions of the warp yarn side surface
of the nozzle block which are above and below respectively of
the slit, and the portion of the nozzle block which is between
the injection port of at least one of the tack-in nozzles and
the slit is provided with the air guide.
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The tack-in apparatus according to the present invention
is adapted to bend the air injection currents from the air
injection ports toward the weft yarn path owing to a Coanda
effect and by the air guides provided on the weft yarn path
sides of the air injection ports, increase the air currents
flowing toward a central portion of the warp yarn opening, and
transfer the end portion of the weft yarn efficiently. Further,
it serves to minimize the air injection currents impinging upon
the warp yarn to reduce the turbulence of the warp yarn.
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Fig. 1 is a plan view of a first mode of embodiment of
the tack-in apparatus according to the present invention.
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Fig. 2 is a sectional view taken along the line A-A in
Fig. 1.
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Fig. 3 is a right side view of the apparatus of Fig. 1.
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Fig. 4 is a sectional view of another mode of embodiment
of the tack-in apparatus according to the present invention.
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The modes of embodiment of the present invention will
now be described on the basis of the drawings. Fig. 1 to Fig.
3 show a mode of embodiment of a tack-in apparatus 10 according
to the present invention. A pair of tack-in apparatuses 10
are provided symmetrically on both sides of a cloth fell 14
of a woven fabric 16 in which an opening of warp yarn 12 being
woven is formed. Out of the two tack-in apparatuses 10, one
tack-in apparatus is provided with a weft inserting main nozzle
(not shown) on the anti-woven-fabric side thereof, and the other
tack-in apparatus a suction nozzle 22 for sucking and retaining
a front end of inserted weft yarn on the anti-woven-fabric side
thereof. A weft yarn cutter 20 is provided between the tack-in
apparatus 10 and suction nozzle 22 or weft yarn inserting main
nozzle. Since the basic construction of the two tack-in
apparatuses 10 is symmetric, the construction of the tack-in
apparatus 10 on the side of the suction nozzle 22 will be described
as a typical construction thereof in this mode of embodiment.
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The tack-in apparatus 10 is provided in the vicinity of
a cloth fell 14 with a substantially rectangular nozzle block
24 one side surface of which is opposed to rows of warp yarn
12 in parallel therewith. The nozzle block 24 is provided with
a slit 26 as aweft yarn end guide groove opened in three directions,
i.e., at the side of a reed and weft yarn which are at the discharge
side, and at the side of the cutter, the slit being formed so
as to extend to a position near the cloth fell 14. The upper
and lower edges of a reed-side end portion of the weft yarn
end guide groove 26 are provided with vertically diverging guide
surfaces 28 so that a weft yarn end 18a is introduced reliably
into the weft yarn end guide groove 26.
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The nozzle block 24 is provided with a pair of tack-in
nozzles 30 formed of a first nozzle 31 positioned above the
slit 26 and a second nozzle 32 positioned below the slit 26.
Injection ports 31a, 32a of the first nozzle 31 and second nozzle
32 are opened in the side surface 24a of the nozzle block 24
which is on the side of the warp yarn 12, and these injection
ports are opposed to a warp yarn opening. The axis of an air
injection current from the first nozzle 31 is set so that the
axis extends from a position diagonally above a plane, which
extends from a surface of a woven fabric 16, so as to cross
the center of warp yarn opening, while the axis of an air injection
current from the second nozzle 32 is set so that the axis extends
from a position diagonally below the plane, which extends from
the surface of the woven fabric 16, so as to cross the center
of the warp yarn opening.
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The first nozzle 31 and second nozzle 32 of the tack-in
nozzles 30 are connected to a pair of air supply pipes 33
respectively, and each air supply pipe 33 to a pressure air
source provided with a regulator (not shown) and the like via
an electromagnetically driven type change-over valve.
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A projection-like air guide 35 adjacent to a lower side
of a circumferential portion of the injection port 31a of the
first nozzle 31 and projecting toward the warp yarn 12 is formed
between the injection port 31 in the side surface 24a of the
nozzle block 24 and slit 26. The air guide 35 is formed by
extending the nozzle block 24 from the portion thereof which
is above the slit 26. An inclined surface 35a of the air guide
35 contacts a lower side of the circumferential portion of the
injection port 31a, and extends diagonally so as to approach
the weft yarn path as the inclined surface comes closer to a
free end of the air guide 35. A projection-like air guide 36
extending toward the warp yarn 12 is also provided similarly
on an upper side of a circumferential portion of the injection
port 32a of and adjacently to the second nozzle 32. An inclined
surface 36a of the air guide 36 also extends diagonally so as
to approach the weft yarn path as the inclined surface comes
closer to a free end of the air guide 36.
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As shown in Fig. 3, an injection port of a weft yarn end
releasing nozzle 34 is opened in a rear wall portion of the
slit 26 of the nozzle block 24. The axis of an air injection
current from the weft yarn end releasing nozzle 34 is set so
as to extend toward a discharge side. The weft yarn end releasing
nozzle 34 is connected to the air supply pipe 36, and an air
supply pipe 43 a pressure air source provided with a regulator
and the like, via an electromagnetically driven type change-over
valve.
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An injection port of a weft yarn gripping nozzle 38 is
opened in an upper surface out of a pair of mutually opposed
inner surfaces of the slit 26 of the nozzle block 24. A weft
yarn end gripping bore 42, a through bore formed so as to be
opposed to the weft yarn end gripping nozzle 38 and extending
perpendicularly to the outer side of the nozzle block 24 is
provided in a lower surface of the slit 26. The axis of an
air injection current from the weft yarn end gripping nozzle
38 is set so that the axis extends to an inner side of the weft
yarn end gripping bore 42. The weft yarn gripping nozzle 38
is connected to an air supply pipe 40, which is connected to
a pressure air source including a regulator and the like, via
an electromagnetically driven type change-over valve. Each
change-over valve is connected to a control unit adapted to
electromagnetically drive the valve in accordance with a
predetermined program.
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The operation of this tack-in apparatus 10 will now be
described. First, after the weft yarn is inserted, the opening
of the warp yarn 12 is closed and then opened in an opposite
phase, and an end portion of the weft yarn 18 enters the slit
26 of the nozzle block 24 owing to a forward movement of a reed
(not shown). During this time, a front end portion of the weft
yarn 18 is caught by the suction nozzle 22. The weft yarn 18
is then cut with the cutter 20 at a point in time at which the
reed moves back slightly after a beating operation is carried
out. At this weft yarn cutting time, the weft yarn end gripping
nozzle 38 is opened, and an air current is injected from the
same nozzle 38 toward the weft yarn gripping bore 42. The end
18a of the cut weft yarn is drawn by the air current from the
weft yarn end gripping nozzle 38, and moored in the weft yarn
end gripping bore 42, the weft yarn end 18a being gripped in
advance of a tack-in operation.
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When the reed further moves back, the subsequent weft
insertion is carried out with predetermined timing. The weft
yarn end releasing nozzle 34 and tack-in nozzles 30 are opened
with predetermined timing respectively, and the weft yarn end
gripping nozzle 38 is closed. As a result, the air current
from the weft yarn end gripping nozzle 38 decreases gradually,
and stops finally, while the air injection currents from the
weft yarn end releasing nozzle 34 and tack-in nozzles 30 increase
gradually, and attain predetermined flow rates at predetermined
time respectively. Therefore, the holding power of the weft
yarn end gripping nozzle 38 decreases gradually, and the weft
yarn end 18a is blown from an end portion of the woven fabric
16 toward the discharge side by the air injection current from
the weft yarn end releasing nozzle 38, and placed in a stretched
state in an injection current working zone of the tack-in nozzles
30. The front weft yarn end 18a in this condition is then blown
by the air injection current from the tack-in nozzles 30 into
the opening of the warp yarn 12 and tacked in. The opened
state of the tack-in nozzles 30 continues until an instant in
the vicinity of that of the completion of the weft inserting
operation, and the nozzles are thereafter closed. Even after
the closing of the tack-in nozzles, the residual air continues
to be injected from the tack-in nozzles 30 for a predetermined
period of time as the injection rate decreases gradually.
Accordingly, the weft yarn end 18a kept in a tacked-in state
is bound to the closed warp yarn 12 with the inserted weft yarn
18 owing to the closing of the weft yarn opening, and then beaten
up, so that a tacked-in selvage is formed on an end portion
of the woven fabric 16.
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According to the tack-in apparatus 10 of this mode of
embodiment, the air guides 35, 36 adjacent to the injection
ports 31a, 32a are formed between the injection ports 31a, 32a,
which are in the side surface 24a of the nozzle block 24, of
the tack-in nozzles 30 and slit 26 which constitutes a weft
yarn path. Therefore, the air currents injected from the
injection ports 31a, 32a are bent toward the weft yarn path
owing to the Coanda effect, and the air current flowing toward
the central portion of the opening of the warp yarn 12 increases.
This enables the weft yarn end 18a to be blown forcibly into
the warp yarn opening with a high efficiency and put in a stretched
state, and a firm and excellent tacked-in selvage to be formed.
The quality of the woven fabric can be kept excellent with the
occurrence of air injection current which impinges upon the
warp yarn minimized and without causing the turbulence of the
warp yarn 12 and the breakage thereof to occur. Especially,
during the formation of a pile woven fabric, a difference between
the condition of formation of pile in a central portion of the
woven fabric and that of formation of pile in the portion thereof
which is in the vicinity of a selvage does not occur, so that
a uniform and high-quality woven fabric is obtained.
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The upper and lower air currents injected from the
injection ports 31a, 32a meet each other after they are bent
and flow toward the air guides. Therefore, when these air
injection currents meet each other, they cushion the shock,
which occurs at this time, with respect to each other.
Consequently, the occurrence of a turbulent flow is prevented,
and the convergence of the injection air currents becomes high.
Therefore, it becomes possible to minimize the cross for
improving the convergence of injection currents of the axes
of the tack-in nozzles, reduce a turbulent flow occurring when
the injection air currents meet each other, and prevent the
diffusion of the air currents, which is ascribed to a turbulent
flow thereof, and a decrease in the velocity of flow of the
air currents. This also serves to minimize the air currents
impinging upon the warp yarn 12.
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In the tack-in apparatus 10 of this mode of embodiment,
the side surfaces 35b, 36b of the air guides 35, 36 may also
be formed as shown in Fig. 4, in such a manner that each of
these side surfaces is spaced slightly from the injection ports
31a, 32a, and formed at right angles to the side surface 24a
of the nozzle block 24. The number of the injection ports of
the tack-in nozzles is not limited to two, i.e. one each on
the upper and lower side positions. These injection ports may
be provided in either one of the upper and lower positions,
or not less than two pairs of injection ports may also be provided.
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In the tack-in apparatus according to the present
invention, the injection air currents from the tack-in nozzles
are bent toward the air guides owing to a Coanda effect thereof,
concentrated on the weft yarn path and flow toward the weft
yarn opening. Therefore, the injection air currents
efficiently transfer the weft yarn end into the warp yarn opening,
and can be tacked in reliably. Moreover, the diffusion of the
injection air currents can be suppressed, and the turbulence
of the warp yarn due to the air currents can be reduced.
Especially, since the air guides are formed so as to have inclined
surfaces at the sides thereof which are near the injection ports,
the injection air currents can be bent toward the weft yarn
path, so that the convergence of the injection air currents
can be improved.
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When the injection ports of the tack-in nozzles are opened
in the portions of a nozzle block having a slit along the weft
yarn path which are above and below the slits, the weft yarn
end can be held reliably owing to the slit until the tack-in
time, and released reliably by a weft yarn releasing nozzle
at the tack-in time. The injection air currents from the upper
and lower tack-in nozzles are bent toward the air guides owing
to a Coanda effect, and the air currents flowing toward the
central portion of the warp yarn opening increase and become
strong. Since, during this time, the upper and lower air
injection currents meet each other after they flow along the
air guides, the occurrence of the interference of the air
currents with each other and a change of the air currents into
a turbulent flow can be prevented when the air currents meet
each other, so that the diffusion of the air currents and a
decrease in the velocity of flow thereof which are ascribed
to the occurrence of a turbulent flow can be suppressed.
Accordingly, it becomes possible to prevent the occurrence of
turbulence of the warp yarn, forcibly blow the weft yarn end
into the warp yarn opening and put the same in a stretched state,
and form a firm and excellent tacked-in selvage.
